Inflammatory and traumatic lesions of the knee and ankle: comparison of 0.23 T and 2 T MRI.

Fifty-six patients with traumatic and 117 patients with inflammatory lesions of the knee and ankle were examined with a 2 T (69 examinations) or 0.23 T (104 examinations) MR system. The quality of all images was assessed by the consensus of three radiologists on a scale of diagnostic (3+, 2+) and nondiagnostic (1+) image quality. More than 90% of images from both systems were diagnostic. However, the proportion of 3+ quality images was significantly higher (p less than 0.001) at the magnetic field strength of 2 T (81% = 56/69 versus 49% = 51/104 at 0.23 T). Motion artifacts were the main cause of reduced image quality independent of field strength. In patients with traumatic and inflammatory diseases of the knee and ankle, high field imaging at 2 T provided better image quality than low field imaging at 0.23 T.